Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![### Thermodynamic Reactions
Consider the following set of reactions:
1. **Reaction 1:**
\[
\text{CO} + \frac{1}{2} \text{O}_2 \rightarrow \text{CO}_2, \quad \Delta H = -283 \, \text{kJ/mol}
\]
- This reaction describes the oxidation of carbon monoxide (CO) to carbon dioxide (CO₂). The enthalpy change (\(\Delta H\)) for this reaction is -283 kJ/mol, indicating it is an exothermic process.
2. **Reaction 2:**
\[
\text{C} + \text{O}_2 \rightarrow \text{CO}_2, \quad \Delta H = -393 \, \text{kJ/mol}
\]
- This reaction involves the direct combustion of carbon (C) with oxygen (O₂) to form carbon dioxide (CO₂). The enthalpy change (\(\Delta H\)) is -393 kJ/mol, showing that this is also an exothermic reaction.
### Explanation
Both reactions are examples of combustion processes that release energy, as indicated by the negative enthalpy values. The differences in \(\Delta H\) values between these reactions can be utilized to understand thermodynamic principles such as Hess’s Law, which facilitates the calculation of enthalpy changes for reactions that might not be directly measurable.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9b0e7686-0c0d-4eba-ac81-54e736b47f2f%2Fe3c913aa-8b12-48b6-93c7-bbda4f53edc2%2Fz2gxdin_processed.jpeg&w=3840&q=75)
![**Determining the Enthalpy for Reaction 1 Reversed**
**Reversed Reaction:**
\[ \text{CO}_2 \rightarrow \text{CO} + \frac{1}{2}\text{O}_2 \]
To find the enthalpy for the reversed reaction, express your answer numerically in kilojoules per mole.
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Enthalpy of reaction is Defined as change in enthalpy of reaction at constant pressure.
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